1. Field of the Invention
The present invention relates to a coating and developing treatment method and a coating and developing treatment system for a substrate.
2. Description of the Related Art
In a photolithography process in semiconductor device fabrication processes, for example, a resist coating treatment for forming a resist film on the surface of a wafer, a developing treatment for performing developing treatment for the wafer after being exposed in a pattern, and a heat treatment, a cooling treatment, and so on performed before the coating treatment, before and after an exposure processing, and after the developing treatment, are performed. These treatments are performed in respective processing units disposed independently for respective treatments, and these processing units are integrated as a coating and developing treatment system so that it can perform a series of the above treatments subsequently. Incidentally, the exposure processing is performed in an aligner usually disposed adjacent to the coating and developing treatment system.
Conventionally, the coating and developing treatment system has a load/unload section for carrying a substrate into/out of the coating and developing treatment system, a coating treatment unit, a developing treatment unit, a heat treatment unit, and so on, and is composed of a processing zone for performing most of the wafer treatments mentioned above and an interface section for carrying the wafer between the processing zone and the aligner disposed outside the system.
When the wafer treatments are performed in the coating and developing treatment system, air which is cleaned by an air purifier and so on is supplied as a down flow into the coating and developing treatment system in order to prevent impurities such as fine particles from adhering to the wafers, while an atmosphere inside the coating and developing treatment system is exhausted, so that the wafer can undergo the treatments in a clean state.
In recent years, however, an exposure technology utilizing light with a shorter wavelength (157 nm, for example) is being developed in order to form a finer, more precise circuit pattern. Consequently, when the wave with a short wavelength is utilized, it is worried that impurities at a molecular level, for example, oxygen, ozone, vapor, and so on, which do not cause any problem conventionally, give an adverse effect on the exposure processing so that a precise circuit pattern may not be formed.
Herein, a method of carrying the substrate into a chamber where airtightness can be maintained before the exposure processing for the wafer, and thereafter removing impurities which adhere on the surface of the wafer by reducing the pressure inside the chamber to a predetermined pressure, are considered. In this case, however, when the impurities are to be removed inside the chamber in which a predetermined condition is set, irrespective of the amount of the impurities adhering to the wafer, it should be taken into consideration that an excessive removing process or an insufficient removing process may be carried out.